Definition. GerdQ. The Thai version of GerdQ was translated from the English version. The contents of the GerdQ were tested by back translation from Thai to English by 5 personnel who are fluent in English and all showed the consistent contents. The reliability of the GerdQ was validated in 22 volunteers completing the questionnaire twice with 3 hours in between and showed no significant difference of the mean score (5.14+ 2.34 vs 6.23+ 1.57, p=0.07) and the number of subjects with GERD diagnosed by the GerdQ (2 vs 5, Fisher's extact test, p=0.21) .